Creation of a Simple Shopping Script (or modification)

I am creating a website that will sell codes for online games (legal codes that I buy through wholesale). When I purchase these codes they come to me by courier. So I want a script made that will allow me to login to the website admin area and manually type in the codes that I got by courier and they will be in the system. When people visit the site, they can browse the categories, search etc. and find the code that they want. They can then purchase this code and pay by PayPal, credit card (via 2CO), maybe google checkout, and then once the payment has been received the code MUST be automatically sent to them via email. This code which is sent out by email must then be removed from the system, or somehow marked in the system as used so that it doesn't get sent out again. I don't want to spend a fortune on this, I just need it to allow me to upload codes and then people to buy them and have them automatically emailed so that they do not have to wait. The site must be secure etc. and major payments accepted. To summarise: 1) Must allow me to add codes via admin panel 2) Must allow creation of categories and different types of codes 3) Buyers should be able to pay by paypal and credit card (preferrably through 2CO as I already have an acount) 4) Codes must be removed or marked in the system, as the same code cannot be sent out twice 5) Must be secure Please do not post proposals that are junk etc. I will happily consider new freelancers and stuff - so please submit your proposals. The script does not have to be unique, it could be a modification of a shopping script already made.